Device for folding box blanks



p 22, 1964 c. A. GOVATSQS 3,149,544

. DEVICE FOR FOLDING BOX BLANKS Filed Feb. 15, 1962 5 Sheets-Sheet 1Sept. 22, 1964 c. A. GOVATSOS DEVICE FOR FOLDING BOX BLANKS 5Sheets-Sheet 2 Filed Feb. 15, 1962 P 22, 1964 c. A. GOVATSOS 3, ,5 4.

DEVICE FOR FOLDING BOX BLANKS Filed Feb. 15, 1962 3 Sheets-Sheet I5 I ze 4 66 [W w lweiii'or 6 8 CiaarZe'sflaovallsos,

United States Patent DEVICE FOR FOLDING BOX BLANKS Charles A. Govatsos,33 Westgate Road, Wellesiey, Mass.

Filed Feb. 15, 1%2, Ser. No. 173,494 7 Claims. (Ci. 93-51) Thisinvention relates in general to devices for folding box blanks and moreparticularly concerns a new and improved die and plunger fabricatedprincipally from a relatively thin ply of laterally resilient plasticmaterial and adapted to fold a lock type box blank in a single operationby means of the plunger forcing the blank through the die.

Typically, box folding machines have been mechanically complicatedaffairs employing a relatively large number of moving parts arranged tofunction in timed cooperation with one another. If the box that is to beset up is of the lock type in which slits and ears at each corner mustbe interlocked, the machine becomes even more complicated because of theneed to open the slits and then insert the ears at the proper moment.

Recently, the machinery needed to fold boxes of the above type has beensimplified by the use of a die which has been formed with contouredgrooves and ribs adapted to fold a box blank that is passed through bymeans of a reciprocating plunger.

While the die and plunger type of box folding machine is a good dealsimpler than those machines previously available, they are not entirelyeffective in bringing the ears into positive locking engagement with theslits. Furthermore, since any die and plunger set can accommodate but asingle size blank, it is necessary that a die and plunger be availablefor each box size which must be set up. This represents a rather largecapital outlay since the die and plunger are normally made from steeland are quite expensive to produce because of the tooling involved inthe making of the die molds.

Accordingly, it is an object of the present invention to provide animproved die and plunger for use in setting up box blanks.

Another object of this invention is to provide a lowcost, easilyfabricated die and plunger for use in box folding operations.

Still another object of this invention is to provide a device forsetting up lock type box blanks so as to produce a positive lockingengagement between the ears and slits.

Yet another object of this invention is to provide a onepiecebox-forming die of laterally resilient material in which selectedportions are disposed for yieldingly engaging portions of a box blank.

A further object of this invention is to provide novel means forpreventing the formation of cracks and splits at joints of sheetmaterial subjected to high stresses.

More particularly, this invention features a box-forming die and plungerfabricated from a relative thin ply of hard but laterally resilientplastic material and adapted to fold and lock in a single operation alock type box blank. As another feature of this invention, Wing elementsare provided at opposite ends of the plunger for engaging the ears afterthey have been passed through their respective slits and deflecting theminwardly so as to lock each ear in position.

A further feature of this invention relates to the use of resilientdepending walls formed along the die opening and adapted to fold thehinged side panels of the blank somewhat beyond their normal foldedposition in order to compensate for the tendency of the folded sidepanels to bow outwardly, particularly in their center portions. Butthese and other features of the invention, along 3,149,544 PatentedSept. 22, 1964 with further objects and advantages thereof will becomemore readily apparent from the following detailed description taken inconnection with the accompanying drawings in which:

PEG. 1 is a view in perspective of a box of the type that may be foldedby operation of the die and plunger of this invention,

FIG. 2 is a top plan view of the plunger made according to thisinvention,

FIG. 3 is a top plan view of a die made according to the invention,

FIG. 4 is a cross-sectional View taken along the line A of FIG. 3,

FIG. 5 is a fragmentary top plan view showing the die, the plunger and abox blank just starting to be passed through the die opening,

FIG. 6 is a cross-sectional view taken along the line 66 of HG. 5,

FIG. 7 is a view similar to FIG. 5 but showing a further stage in thefolding operation,

FIG. 8 is a crosssectional view taken along the line 8i-i of FIG. 7,

FIG. 9 is a cross-sectional view taken along the line 99 of FIG. 7,

FIG. 10 is a sectional view in end elevation showing a still furtherstage in the folding operation,

FIG. 11 is a top plan view showing a plunger somewhat modified inconstruction from that of FIG. 2,

H6. 12 is a cross-sectional view taken along the line 12-42 of FIG. 11,and,

FIG. 13 is an end elevation of the plunger of FIG. 11.

Referring now to FIG. 1 of the drawings, the reference character 10generally indicates a fully set up paper board box having a rectangularcenter panel 12, side panels 14 hinged along opposite sides of thecenter panel and end panels 16 hinged along opposite ends of the centerpanel. A tuck flap or tab 18 with an outwardy projecting locking car 20thereon is integral with each end of each side panel 14 and each endpanel 16 is provided with angled slits 22 for receiving the locking ears20.

Referring now more particularly to FIGS. 2 and 3, the improved apparatusfor setting up the box blanks includes a plunger 24 (FIG. 2) and a die25 (FIG. 3). The plunger is generally rectangular in plan View andpreferably is molded from a hard, tough, relatively stiff and slightlyresilient plastic material such as butadiene or any other moldablematerial that presents a relatively smooth hard surface, possesses arather high degree of lateral stability in sheet or molded form and yetdisplays good flexing characteristics.

The plunger shown has a flat upper portion 26 with a slightly flareddepending skirt or flange 23. The dimensions of the plunger correspondto those of the panel 12 so that the lower edges of the flange 28 willgenerally follow the fold lines of the box blank. Mounted at each end ofthe plunger is an upright wing 30 which is separately formed of metaland attached by bolts, rivets or the like to a flattened should-erportion 32. The side edges of the wing 30 are somewhat inclined and arecurved outwards for reasons that will presently appear. It will be notedthat the curved portions of the wing 30 extend beyond the shoulder 32 todefine a reentrant opening 34 with the flange of the plunger.

In practice, the plunger 24 is attached to a reciprocating element suchas a piston for apneumatic cylinder and is provided with severalopenings 36 to accommodate connecting bolts.

Referring now to FIG. 3, the die 25 is formed from the same plasticmaterial as the plunger 24 and is rectangular in plan view having arather Wide fiat flange 38 with marginal openings 40 for securing thedie to a stand or base in register with the plunger 24. The die isformed elegant with a generally rectangular central opening 42downwardly therethrough of a size corresponding to that of the panel 12and permitting passage of this panel therethrough. The die includesintegral raised end shoulders 44 and recessed side shoulders 46 whichdefine the opening 42 and present curved surfaces to fold first the endand then the side panels of the box blank upwardly as the blank isforced downwardly therethrough as shown in FIGS. 5-10. Depending end andside walls 48 and 59 extend downwardly from the shoulders 44 and 46respectively to define an abbreviated chute down which the box ispassed.

The side shoulders 46 and their depending walls 5% are curved inwardlyas best shown in FIGS. 9 and 10, to restrict the Width of the opening4-2 to a certain extent. It will be noted in FIG. 3 that the curved sidewall sections 50 are not directly connected to the end walls 48 butrather are separated from them by slits 54 which follow the corners ofthe opening 42, angle inwardly across the curved shoulder 46 andterminate in small circular open ings 56. This arrangement together withthe natural resiliency of the die material permits the wall sections 50to flex to a certain extent and to spread outwardly under the force ofthe plunger as it passes through the opening. The curved side shoulders46 and side walls 5% serve to erect the side panels 14 of the box blankand, by reason of their curved and flexible construction, fold the sidepanels 14 in excess of 90 so as to compensate for the tendency of theside panels to return to their original flat condition. The end resultis that when the box is fully set up, its side panels areperpendicularly erect and longitudinally straight.

In order to prevent the formation of cracks which might otherwisedevelop because of the stresses generated by constant flexing of thecurved wall and shoulder sections, the slots 54 have been terminatedwith the circular openings 56. These openings, as best shown in FIG. 4,are charnfered so s to present a thin inner edge 53. By forming the thininner edge about the opening 56, the tendency of the material to crackor split is greatly reduced. This is due to the fact that thin materialundergoes much lower stresses when flexed than does thick material. Byway of explanation, it will be appreciated that the stress present onthe surface of a sheet that has been bent under pressure is dependentupon its distance from the center of flex. Assuming, for example, thatmaterial one inch thick is bent under pressure, the outer curved surfacewill be under a tension stress whereas the inner curved surface will becompressed. The amount of tension in the region of the outer curvedsurface would be much less than that for a similar material two inchesthick since the distance to the center of the fiex is less. Accordingly,by chamfering the edges of the circular opening 56 the stresses in thearea where a crack would normally originate are substantially reduced.

Referring again to FIG. 3, it will be noted that the end shoulders 44are each provided with a rather wide vertical rib 60 with narrower ribs62 formed parallel thereto and adjacent to the corners of the opening42.

In order to clarify the functioning of the die and plunger, reference ismade to FIGS. 5-10 which show a box blank in the various stages ofassembly. Referring now to FIG. 5, a blank is shown in the first stageof the folding operation with the plunger 24 having pressed the blankdown over the end of shoulders 44. At this point, the side panels 14 arestill in a horizontal position whereas the end panel 16 has been raisedto a vertical position by means of the shoulder 44.

As the plunger moves the blank further down through the opening 42 theside shoulders 46 meet with the side panels 14 to urge them into anupright position. Simultaneously, the wings 30 cooperate with the ribs62 to open up the slits 22 by the rib pushing inwardly against the endpanel on one side of the slit while the wing pushes outwardly againstthe end panel on the other side of the 4 slit. As the slit opens thelocking ear 2! is passed through and is received in the reentrantopening 34 of the plunger.

The plunger continues downward with the curved walls 54} being flexedapart while bending the side panels 14 in the manner described above. Atthe bottom of the stroke the top edges of the box clear the bottom edgesof the die and the plunger is retracted. The box is stripped from theplunger as it retracts by the upper edges of the end panels buttingagainst the lower edges of the end walls 48. Also, as the plungerretracts the curved and inclined edges of the Wings 30, which had beenbetween the looking ears 20 and the end panel 16, move up and out ofthis position and thereby wipe the locking ears to insure a positivelocking engagement with the edges of the slits 22.

In FIGS. 1ll3 a modification of the plunger is illustrated. In thisembodiment a plunger 64 is molded entirely in one piece with wings 66formed as an integral part of the plunger body rather than as separateelements as in the principal embodiment. The configuration is similar tothat of the plunger in FIG. 2 with the exception that a skirted flange65: has been made somewhat deeper than that of the plunger 24 and a wing66, of a design similar to that of the wing 3%, depends from each end ofthe flat top portion of the plunger.

While the invention has been described with particular reference to theillustrated embodiment, it will be understood that numerousmodifications will appear to those skilled in the art without departingfrom the invention. For example, a wide variety of materials may beemployed to form the die and plunger parts. Laminated fiber glass, forexample, would possess the proper strength, rigidity and flexibilitycharacteristics required for the parts. Other materials may also be usedto advantage.

Having thus described my invention, what I claim and desire to obtain byLetters Patent of the United States is:

1. Apparatus for setting up into box form a flat blank having arectangular bottom panel together with hinged side and end panels, tuckflaps with outwardly projecting locking ears integral with the ends ofthe side panels and slits in each end panel for receiving the adjacentears in locking engagement, comprising a one piece die having agenerally rectangular opening formed therein of a size generallycorresponding to the dimensions of said bottom panel, said die beingformed from a relatively thin ply of a laterally resilient plasticmaterial having a smooth hard outer surface and being of substantiallyconstant thickness, downwardly curved side and end shoulders formedalong said die opening for folding said side and end panels upwardlywhen said blank is forced downwardly through said opening, inwardlycurved flexible side walls depending from said side shoulders andnormally restricting the size of said opening for yieldingly engagingsaid side panels, said die being formed with recesses between said sideand end shoulders to permit said side walls to flex under pressure, endwalls depending from said end shoulders, ribs formed on said endshoulders and extending down said end walls, a plunger of generally thesame dimensions as said bottom panel and wing members mounted onopposite ends of said plunger, said wing members in cooperation withsaid ribs being adapted to open said slits by applying opposingpressures to diagonally opposite sides of each of said slits, saidshoulders and said side walls being adapted to fold said ears into saidslits as said plunger advances said blank through said opening, saidwings being further adapted to wipe said ears inwardly upon retractionof said plunger.

2. Apparatus for setting up into box form a fiat blank havingarectangular bottom panel together with hinged side and end panels, tuckflaps with outwardly projecting locking ears integral with the ends ofthe side panels and slits in each end panel for receiving the'adjacentears in locking engagement, comprising a thin-walled one piece diehaving a generally rectangular opening formed therein of a sizegenerally corresponding to the dimensions of said bottom panel, said diebeing formed of a ply of laterally resilient plastic material ofsubstantially constant thickness, downwardly curved side and endshoulders formed along said die opening for folding said side and endpanels upwardly when said blank is forced downwardly through saidopening, flexible side walls freely depending from said side shouldersand normally restricting the size of said opening for yieldinglyengaging said side panels, end walls depending from said end shoulders,ribs formed on said end shoulders and extending down said end walls, aplunger adapted to force said blank through said opening and curved wingmembers mounted on opposite ends of said plunger, said wing members incooperation with said ribs being adapted to open said slit by applyingopposing pressures on opposite sides of each of said slits, saidshoulders and said side walls being adapted to fold said ears into saidslits as said plunger advances said blank through said opening, saidwings being further adapted to wipe said ears inwardly when the formedblank is stripped from said plunger.

3. Apparatus for setting up into box form a flat blank having arectangular bottom panel together with hinged side and end panels, tuckflaps with outwardly projecting locking ears integral with the ends ofthe side panels and slits in each end panel for receiving the adjacentears in looking engagement, comprising a one piece die having an openingformed therein generally corresponding to the dimensions of said bottompanel, said die being formed of a ply of moldable laterally resilientplastic material of substantially constant thickness, shoulders formedabout said die opening for folding said side and end panels at generallyright angles to said bottom panel when said blank is forced flatwisethrough said opening and freely extending flexible side walls dependingfrom said shoulders and curving inwardly to normally restrict the sizeof said opening for yieldingly engaging said side panels.

4. Apparatus for setting up into box form a fiat blank having arectangular bottom panel together with hinged side and end panels, tuckflaps with outwardly projecting locking ears integral with the ends ofthe side panels and slits in each end panel for receiving the adjacentears in locking engagement, comprising a die having an opening formedtherein generally corresponding to the dimensions of said bottom panel,said die being formed of a laterally resilient plastic material,shoulders formed about said die opening for folding said side and endpanels at generally right angles to said bottom panel when said blank isforced flatwise through said opening and thin-walled flexible side wallsdepending from said shoulders for yieldingly engaging said side panels.

5. Apparatus for setting up into box form a flat blank having arectangular bottom panel together with hinged side and end panels, tuckflaps with outwardly projecting locking ears integral with the ends ofthe side panels and slits in each end panel for receiving the adjacentears in locking engagement, comprising a one piece thin-walled diehaving an opening formed therein generally corresponding to thedimensions of said bottom panel, said die being formed of a material ofsubstantially constant thickness, shoulders formed about said dieopening for folding said side and end panels upwardly when said blank isforced downwardly through said opening in a fiatwise position, andflexibly connected sidewalls integral with said die and extending freelyfrom at least an opposite pair of said shoulders, said side wallspresenting curved surfaces normally restricting the size of said dieopening for yieldingly engaging said side panels.

6. Apparatus for setting up into box form a flat blank having arectangular bottom panel together with hinged side and end panels, tuckflaps with outwardly projecting locking ears integral with the ends ofthe side panels and slits in each end panel for receiving the adjacentears in locking engagement, comprising a thin-walled one piece diehaving an opening formed therein of a size generally corresponding tothe dimensions of said bottom panel said die being formed of a laterallyresilient and substantially non-compressible plastic material ofgenerally constant thickness and shoulders formed about said die openingfor folding said side and end panels upwardly when said blank is forceddownwardly through said opening in a fiatwise condition.

7. Apparatus for setting up into box form a flat blank having arectangular bottom panel together with hinged side and end panels, tuckflaps with outwardly projecting locking ears integral with the ends ofthe side panels and slits in each end panel for receiving the adjacentears in locking engagement, comprising a die having an opening formedtherein generally corresponding to the dimensions of said bottom panel,said die being formed of a self supporting laterally resilient plasticmaterial, shoulders formed about said die opening for folding said sideand end panels at generally right angles to said bottom panel when saidblank is forced flatwise through said opening and thin-Walled flexibleside walls depending from said shoulders for yieldingly engaging saidside panels, said die being formed with arcuate reentrant recesses atthe juncture of said side Walls and said shoulders, the edges of saidrecesses being chamfered.

References Cited in the file of this patent UNITED STATES PATENTS2,512,161 Ledel June 20, 1950 2,516,624 Guyer July 25, 1950 2,580,189Pagendarm Dec. 25, 1951 2,626,545 Samsing July 27, 1953 2,852,897Woodworth Sept. 23, 1958 2,899,849 Laughter et al Aug. 18, 19592,995,991 Trelford Aug. 15, 1961

3. APPARATUS FOR SETTING UP INTO BOX FORM A FLAT BLANK HAVING ARECTANGULAR BOTTOM PANEL TOGETHER WITH HINGED SIDE AND END PANELS, TUCKFLAPS WITH OUTWARDLY PROJECTING LOCKING EARS INTEGRAL WITH THE ENDS OFTHE SIDE PANELS AND SLITS IN EACH END PANEL FOR RECEIVING THE ADJACENTEARS IN LOCKING ENGAGEMENT, COMPRISING A ONE PIECE DIE HAVING AN OPENINGFORMED THEREIN GENERALLY CORRESPONDING TO THE DIMENSIONS OF SAID BOTTOMPANEL, SAID DIE BEING FORMED OF A PLY OF MOLDABLE LATERALLY RESILIENTPLASTIC MATERIAL OF SUBSTANTIALLY CONSTANT THICKNESS, SHOULDERS FORMEDABOUT SAID DIE OPENING FOR FOLDING SAID SIDE AND END PANELS AT GENERALLYRIGHT ANGLES TO SAID BOTTOM PANEL WHEN SAID BLANK IS FORCED FLATWISETHROUGH SAID OPENING AND FREELY EXTENDING FLEXIBLE SIDE WALLS DEPENDINGFROM SAID SHOULDERS AND CURVING INWARDLY TO NORMALLY RESTRICT THE SIZEOF SAID OPENING FOR YIELDINGLY ENGAGING SAID SIDE PANELS.